Methods and compositions for use in treating cancer

ABSTRACT

The invention provides methods and compositions for use in treating diseases associated with excessive cellular proliferation, such as cancer, and intermediates for the synthesis of such compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority from, U.S.patent application Ser. No. 12/653,461, filed Dec. 15, 2009, which is acontinuation of U.S. patent application Ser. No. 12/341,154, filed Dec.22, 2008 (now abandoned), which is a continuation of U.S. patentapplication Ser. No. 10/687,526, filed Oct. 16, 2003 (now U.S. Pat. No.7,470,720), which is a continuation of U.S. patent application Ser. No.10/272,167, filed Oct. 16, 2002 (now U.S. Pat. No. 6,653,341), which isa continuation-in-part of U.S. patent application Ser. No. 09/843,617,filed Apr. 26, 2001 (now U.S. Pat. No. 6,469,182), which is acontinuation of U.S. patent application Ser. No. 09/677,485, filed Oct.2, 2000 (now U.S. Pat. No. 6,365,759), which is a continuation of U.S.patent application Ser. No. 09/334,488, filed Jun. 16, 1999 (now U.S.Pat. No. 6,214,865), which claims benefit of U.S. Provisional PatentApplication No. 60/089,682, filed Jun. 17, 1998 (now lapsed). Thecontents of the earlier filed applications are incorporated by referenceherein in their entirety.

FIELD OF THE INVENTION

This invention relates to methods and compositions for use in treatingcancer and intermediates for the synthesis of such compositions.

BACKGROUND OF THE INVENTION

Cancer is a term used to describe a wide variety of diseases that areeach characterized by the uncontrolled growth of a particular type ofcell. It begins in a tissue containing such a cell and, if the cancerhas not spread to any additional tissues at the time of diagnosis, maybe treated by, for example, surgery, radiation, or another type oflocalized therapy. However, when there is evidence that cancer hasmetastasized from its tissue of origin, different approaches totreatment are typically used. Indeed, because it is not possible todetermine the extent of metastasis, systemic approaches to therapy areusually undertaken when any evidence of spread is detected. Theseapproaches involve the administration of chemotherapeutic drugs thatinterfere with the growth of rapidly dividing cells, such as cancercells.

Halichondrin B is a structurally complex, macrocyclic compound that wasoriginally isolated from the marine sponge Halichondria okadai andsubsequently was found in Axinella sp., Phakellia carteri, andLissondendryx sp. A total synthesis of halichondrin B was published in1992 (Aicher et al., J. Am. Chem. Soc. 114:3162-3164, 1992).Halichondrin B has been shown to inhibit tubulin polymerization,microtubule assembly, beta^(S)-tubulin crosslinking, GTP and vinblastinebinding to tubulin, and tubulin-dependent GTP hydrolysis in vitro. Thismolecule has also been shown to have anti-cancer properties in vitro andin vivo. Halichondrin B analogs having anti-cancer activities aredescribed in U.S. Pat. No. 6,214,865 B1.

SUMMARY OF THE INVENTION

The invention features a compound having the formula:

or a pharmaceutically acceptable salt thereof.

The invention further features compounds that can be employed in thesynthesis of B1939, pharmaceutically acceptable salts thereof, and otherhalichondrin analogs described in U.S. Pat. No. 6,214,865 and methods ofsynthesizing B1939 or a pharmaceutically acceptable salt thereof usingthese compounds:

The invention provides methods of treating cancer in a patient,involving administration of a compound having the formula:

or a pharmaceutically acceptable salt thereof, which is carried out incombination with a second approach to treatment.

The second approach to treatment can involve administration of achemotherapeutic drug to the patient. Examples of types of such drugsinclude antimetabolites, antibiotics, alkylating agents, plantalkaloids, and hormonal agents.

An antimetabolite, such as gemcitabine, can be used in the invention inthe treatment of, for example, non-small cell lung carcinoma, pancreaticcancer, or metastatic breast cancer. An antimetabolite, such ascapecitabine, can also be used in the invention in the treatment of, forexample, breast cancer or colorectal cancer.

An example of a type of antibiotic that can be used in the invention isanthracyclines (e.g., doxorubicin), which can be used in the invention,for example, in the treatment of breast cancer.

Alkylating agents, such as carboplatinum or cisplatinum, can be used inthe invention to treat, for example, non-small cell lung cancer orovarian cancer.

Plant alkaloids, such as irinotecan and topotecan, can be used in theinvention to treat, for example, colorectal cancer, ovarian cancer, ornon-small cell lung carcinoma.

The second approach to treatment can also involve administration of ananticoagulant or antithrombotic agent (e.g., heparin) to the patient.

The invention also provides compositions that include a compound havingthe formula:

or a pharmaceutically acceptable salt thereof, in combination with asecond anti-cancer drug. These drugs include, for example, any of thechemotherapeutic agents mentioned elsewhere herein, as well as others.

Other features and advantages of the invention will be apparent from thefollowing detailed description and the claims.

DETAILED DESCRIPTION OF THE INVENTION

Compounds of general formula 4, e.g., B1939, can be prepared by theroute outlined in Scheme 1.

In formula (I), A is a C₁₋₆ saturated or C₂₋₆ unsaturated hydrocarbonskeleton, the skeleton being unsubstituted or having between 1 and 13substituents, preferably between 1 and 10 substituents, e.g., at leastone substituent selected from cyano, halo, azido, Q₁, and oxo. Each Q₁is independently selected from OR₁, SR₁, SO₂R₁, OSO₂R₁, NR₂R₁,NR₂(CO)R₁, NR₂(CO)(CO)R₁, NR₄(CO)NR₂R₁, NR₂(CO)OR₁, (CO)OR₁, O(CO)R₁,(CO)NR₂R₁, and O(CO)NR₂R₁. The number of substituents can be, forexample, between 1 and 6, 1 and 8, 2 and 5, or 1 and 4. Throughout thedisclosure, numerical ranges are understood to be inclusive.

Each of R₁, R₂, R₄, R₅, and R₆ is independently selected from H, C₁₋₆alkyl, C₁₋₆ haloalkyl, C₁₋₆ hydroxyalkyl, C₁₋₆ aminoalkyl, C₆₋₁₀ aryl,C₆₋₁₀ haloaryl (e.g., p-fluorophenyl or p-chlorophenyl), C₆₋₁₀hydroxyaryl, C₁₋₄ alkoxy-C₆ aryl (e.g., p-methoxyphenyl,3,4,5-trimethoxyphenyl, p-ethoxyphenyl, or 3,5-diethoxyphenyl), C₆₋₁₀aryl-C₁₋₆ alkyl (e.g., benzyl or phenethyl), C₁₋₆ alkyl-C₆₋₁₀ aryl,C₆₋₁₀ haloaryl-C₁₋₆ alkyl, C₁₋₆ alkyl-C₆₋₁₀ haloaryl, (C₁₋₃ alkoxy-C₆aryl)-C₁₋₃ alkyl, C₂₋₉ heterocyclic radical, C₂₋₉ heterocyclicradical-C₁₋₆ alkyl, C₂₋₉ heteroaryl, and C₂₋₉ heteroaryl-C₁₋₆ alkyl.There may be more than one R₁, for example, if A is substituted with twodifferent alkoxy(OR₁) groups such as butoxy and 2-aminoethoxy.

Examples of A include 2,3-dihydroxypropyl, 2-hydroxyethyl,3-hydroxy-4-perfluorobutyl, 2,4,5-trihydroxypentyl,3-amino-2-hydroxypropyl, 1,2-dihydroxyethyl,2,3-dihydroxy-4-perfluorobutyl, 3-cyano-2-hydroxypropyl,2-amino-1-hydroxy ethyl, 3-azido-2-hydroxypropyl,3,3-difluoro-2,4-dihydroxybutyl, 2,4-dihydroxybutyl,2-hydroxy-2(p-fluorophenyl)-ethyl, —CH₂(CO)(substituted or unsubstitutedaryl), —CH₂(CO)(alkyl or substituted alkyl, such as haloalkyl orhydroxyalkyl), and 3,3-difluoro-2-hydroxypent-4-enyl.

Examples of Q₁ include —NH(CO)(CO)-(heterocyclic radical or heteroaryl),—OSO₂-(aryl or substituted aryl), —O(CO)NH-(aryl or substituted aryl),aminoalkyl, hydroxyalkyl, —NH(CO)(CO)-(aryl or substituted aryl),—NH(CO)(alkyl)(heteroaryl or heterocyclic radical), O(substituted orunsubstituted alkyl)(substituted or unsubstituted aryl), and—NH(CO)(alkyl)(aryl or substituted aryl).

Each of D and D′ is independently selected from R₃ and OR₃, wherein R₃is H, C₁₋₃ alkyl, or C₁₋₃ haloalkyl. Examples of D and D′ are methoxy,methyl, ethoxy, and ethyl. In some embodiments, one of D and D′ is H.

The value for n is 1 or preferably 0, thereby forming either asix-membered or five-membered ring. This ring can be unsubstituted orsubstituted, e.g., where E is R₅ or OR₅, and can be a heterocyclicradical or a cycloalkyl, e.g., where G is S, CH₂, NR₆, or preferably O.

Each of J and J′ is independently H, C₁₋₆ alkoxy, or C₁₋₆ alkyl; or Jand J′ taken together are ═CH₂ or —O-(straight or branched C₁₋₅alkylene)-O—, such as exocyclic methylene or ethylene. Q is C₁₋₃ alkyland is preferably methyl. T is ethylene or ethenylene, optionallysubstituted with (CO)OR₇, where R₇ is H or C₁₋₆ alkyl. Each of U and U′is independently H, C₁₋₆ alkoxy, or C₁₋₆ alkyl; or U and U′ takentogether are ═CH₂ or —O-(straight or branched C₁₋₅ alkylene)-O—. X is Hor C₁₋₆ alkoxy. Each of Y and Y′ is independently H or C₁₋₆ alkoxy; or Yand Y′ taken together are ═O, ═CH₂, or —O-(straight or branched C₁₋₅alkylene)-O—. Each of Z and Z′ is independently H or C₁₋₆ alkoxy; or Zand Z′ taken together are ═O, ═CH₂, or —O— (straight or branched C₁₋₅alkylene)-O—.

The invention features compounds of sufficient stability to be suitablefor pharmaceutical development. The invention also featurespharmaceutically acceptable salts of disclosed compounds, disclosednovel synthetic intermediates, pharmaceutical compositions containingone or more disclosed compounds, methods of making the disclosedcompounds or intermediates, and methods of using the disclosed compoundsor compositions. Methods of use include methods for reversibly orirreversibly inhibiting mitosis in a cell, and for inhibiting cancer ortumor growth in vitro, in vivo, or in a patient. The invention alsofeatures methods for identifying an anti-mitotic or anti-cancer agent,such as a reversible or, preferably, an irreversible agent.

Key fragment F-2 exemplified by vinyl iodide compound X2 can be preparedaccording to the procedure of Kishi, et al. (Total synthesis ofhalichondrin B and norhalichondrin B. Aicher, T. D.; Buszek, K. R.;Fang, F. G.; Forsyth, C. J.; Jung, S. H.; Kishi, Y.; Matelich, M. C.;Scola, P. M.; Spero, D. M.; Yoon, S. K. J. Am. Chem. Soc. 1992, 114,3162-4).

Key fragment F-3 can be obtained by DIBALH reduction of thecorresponding methyl ester, XF3, prepared according to the procedure ofStamos, et al. [Synthetic studies on halichondrins: a practicalsynthesis of the C.1-C.13 segment. Stamos, D. P.; Kishi, Y. TetrahedronLett. 1996, 37, 8643-8646]. Key fragment F-1 can be synthesized asdescribed in U.S. Pat. No. 6,214,865.

Using B1793 as a representative example, coupling of the three keyfragments proceeded as outlined in U.S. Pat. No. 6,214,865:Nozaki-Hiyama-Kishi coupling of fragments F-1 and F-2 followed byintramolecular Williamson ether formation furnished tetrahydropyran.Protecting group modification afforded primary iodide. Halogen-metalexchange reaction and coupling with key fragment F-3 furnished a mixtureof diastereomeric alcohols. Additional protecting group manipulation andoxidation followed by an intramolecular Nozaki-Hiyama-Kishi reactionafforded an intermediate, which when oxidized and treated with TBAFunderwent intramolecular hetero-Michael ring closure. PPTs mediatedacetal formation furnished B1793.

One or more hydroxyl groups could be converted to the correspondingamino groups with subsequent coupling with an activated carbonylcomponent. Displacement of the sulfonyl intermediate by carbon orheteroatom nucleophiles could also be readily accomplished to yieldB1939.

B2304 may be prepared as follows.

To a solution of the alcohol, prepared as described in U.S. Pat. No.6,214,865, 2.4 g, in methylene chloride, 29 mL, was addedmethanesulfonyl anhydride, 770 mg. The mixture was stirred for 15minutes, extracted with saturated sodium bicarbonate, dried andchromatographed to give 2.737 g, 100%.

To a solution of the mesylate, 405 mg, in DMF, 0.06 mL, was addeddi-isopropylethylamine, 0.130 mL, followed by benzenethiol, 0.061 mL.After 4 hours and after 22 hours, additional amine, 0.03 mL, andbenzenethiol, 0.015 mL, were added. After 24 hours, the mixture wasdiluted with 5% ethyl acetate/hexane, 1 mL and chromatographed to give409 mg.

To a solution of the sulfide, 1.97 g, in acetonitrile, 16 mL, was addedN-methylmorpholine oxide (NMO), and then a solution of 1.02 g,tetrapropylammonium perruthenate(VII), (TPAP), 38 mg, in acetonitrile, 1mL. After 3.5 hours at room temperature, the mixture was heated to 40°C. for 1 hour. The mixture was cooled and aqueous satd. Sodiumthiosulfate was added, and the mixture partitioned between water andethyl acetate. The usual work-up gave 1.567 g of a brown oil.

To a solution of the pivaloate ester, 1.567 g, in methylene chloride,11.2 mL, at −78° C., was added DIBAL, 2.5 mL of a 1 M solution intoluene. After 15 minutes, additional DIBAL, 0.8 mL, was added. After anadditional 5 minutes, methanol, 0.46 mL, was slowly added followed bywater, 0.2 mL. The mixture was filtered through Celite andchromatographed to give 1.386 g of an oil.

Key fragment F-3 can be obtained by DIBALH reduction of thecorresponding methyl ester, XF3, as described above.

To a solution of the sulfone, 36 mg, in DME, 1 mL, at −40° C. was addedn-butyllithium, 2.8 equivalents. After 35 minutes, a solution of thealdehyde, 42 mg, in DME, 0.5 mL, was added. After 40 minutes, saturatedaqueous ammonium chloride was added, and the mixture extracted withethyl acetate. The usual work-up, followed by chromatography gave 52 mgof an oil.

To a solution of the alcohol, 42 mg, in methylene chloride, 2 mL, wasadded the Dess Martin reagent, 36.4 mg. The mixture was stirred for 30minutes, and ether was added. The mixture was filtered through Celite,washed with saturated sodium bicarbonate, with saturated sodiumthiosulfate, worked up in the usual way, and chromatographed to give 38mg of an oil.

Preparation of SmI₂ Solution

A solution of 1,2-di-iodoethane in 10 mL of THF was added to asuspension of Sm, 0.16 g, in THF, 1 mL. The mixture was stirred for 1hour.

An aliquot of this solution, 0.03 mL, was added to a solution of thesulfone in THF at −78° C. After 5 minutes, additional SmI₂ reagent, 0.05mL, was added. After a few additional minutes, more reagent, 0.25 mL,was added. The cooling bath was removed, and saturated aqueous sodiumbicarbonate, 3 mL, was added. The mixture was partitioned between etherand water, and the usual work-up gave 9.1 mg, 81%, of an oil.

B2302 and B2303. In a glove box, NiCl₂/CrCl₂ (1% w/w, 1.09 g, 8.86 mmol)was added to a solution of B2304 (1.01 g, 0.70 mmol) in THF (600 mL) andDMF (150 mL) at rt. After stirring for 2 days the reaction mixture wastaken out of the glove box, cooled to 0° C., quenched with saturatedaqueous NH₄Cl (300 mL), and stirred at 0° C. for 20 min. After additionof H₂O (100 mL), the two layers were separated, and the aqueous layerwas extracted with EtOAc (5×). The combined organic phases were washedwith brine, dried over Na₂SO₄, concentrated, and purified by columnchromatography (15% EtOAc-hexanes) to furnish a mixture of B2302 andB2303 (0.84 g, 92%) as a solid foam. Although the isomers could beseparated by prep TLC (20% EtOAc-hexanes), they were carried forward asa mixture.

B2301. A mixture of B2302/B2303 (0.79 g, 0.60 mmol) and Dess-Martinperiodinane (0.26 g, 0.60 mmol) in CH₂Cl₂ (30 mL) at rt was stirred for30 min. Additional Dess-Martin periodinane (0.26 g, 0.60 mmol) was addedto the mixture, and stirring was continued for an additional 1.5 h. Themixture was then diluted with Et₂O (100 mL), stirred for 15 min, andfiltered through Celite. The filtrate was washed with saturated aqueousNaHCO₃ (100 mL), and the separated aqueous layer was extracted with Et₂O(3×). The combined organic phases were dried over Na₂SO₄, concentrated,and purified by column chromatography (10% to 15% EtOAc-hexanes) to giveB2301 (0.67 g, 85%) as an oil.

B1793. TBAF (1 M in THF containing 0.5 M imidazole HCl, 4.60 mL, 4.60mmol) was added over 2 min to a solution of B2301 (0.62 g, 0.48 mmol) inTHF (29 mL) at rt, and the resulting mixture was stirred for 18 h. Afterdilution with hexanes (10 mL), the reaction mixture was directly loadedonto a SiO₂ column packed with 50% EtOAc-hexanes and eluted with 50%EtOAc-hexanes (1 L) followed by 10% MeOH/EtOAc to collect a mixture ofintermediates. After solvent removal, the residue was dissolved inCH₂Cl₂ (15 mL) and treated with PPTS (645 mg). After stirring for 1 h atrt, additional PPTS (414 mg) was added, and the resulting whitesuspension was stirred for 4.5 h. The reaction mixture was then directlyloaded onto a SiO₂ column packed with 70% EtOAc-hexanes and eluted with70% EtOAc/hexanes (0.5 L), EtOAc (1 L). Elution with 5% to 10%MeOH/EtOAc furnished pure B1793 (181 mg) and elution with 15% MeOH-EtOAcgave additional semi-pure product, which after purification bypreparative TLC (10% MeOH-EtOAc) provided additional pure B1793 (42 mg).B1793 (total 223 mg, 64%) was obtained as a white solid. HRMS: calcd forC₄₀H₅₈O₁₂+Na 753.3826. Found: 753.3808.

The invention provides methods for treating cancer, involvingadministration of a halichondrin B analog, such as an analog having thefollowing structure:

which is carried out in combination with a second approach to treatment.

There are numerous types of anti-cancer approaches that can be used inconjunction with halichondrin B analog treatment, according to theinvention. These include, for example, treatment with chemotherapeuticagents (see below), biological agents (e.g., hormonal agents, cytokines(e.g., interleukins, interferons, granulocyte colony stimulating factor(G-CSF), macrophage colony stimulating factor (M-CSF), and granulocytemacrophage colony stimulating factor (GM-CSF)), chemokines, vaccineantigens, and antibodies), anti-angiogenic agents (e.g., angiostatin andendostatin), radiation, and surgery.

The methods of the invention can employ these approaches to treat thesame types of cancers as those for which they are known in the art to beused, as well as others, as can be determined by those of skill in thisart. Also, these approaches can be carried out according to parameters(e.g., regimens and doses) that are similar to those that are known inthe art for their use. However, as is understood in the art, it may bedesirable to adjust some of these parameters, due to the additional useof a halichondrin B analog with these approaches. For example, if a drugis normally administered as a sole therapeutic agent, when combined witha halichondrin B analog, according to the invention, it may be desirableto decrease the dosage of the drug, as can be determined by those ofskill in this art. Examples of the methods of the invention, as well ascompositions that can be used in these methods, are provided below.

Chemotherapeutic drugs of several different types including, forexample, antimetabolites, antibiotics, alkylating agents, plantalkaloids, hormonal agents, anticoagulants, antithrombotics, and othernatural products, among others, can be used in conjunction withhalichondrin B treatment, according to the invention. Specific,non-limiting examples of these classes of drugs, as well as cancers thatcan be treated by their use, are as follows.

Antimetabolite drugs that halichondrin B analogs can be used withinclude, e.g., methotrexate, purine antagonists (e.g., mercaptopurine,thioguanine, fludarabine phosphate, cladribine, and pentostatin), andpyrimidine antagonists (e.g., gemcitabine, capecitabine, fluorouracil(e.g., 5-FU), cytarabine, and azacitidine). Use of these agents to treatparticular types of cancers is well known in the art, and these agentscan be used in combination with halichondrin B analogs to treat theseand other types of cancers. As specific, non-limiting examples, ahalichondrin B analog can be used with gemcitabine in the treatment ofnon-small cell lung carcinoma, pancreatic cancer, or metastatic breastcancer. In an additional example, a halichondrin B analog can be used inconjunction with capecitabine in the treatment of breast or colorectalcancers.

As is noted above, another class of chemotherapeutic drugs with whichhalichondrin B analogs can be used includes anticancer antibiotics.These include, for example, anthracyclines (e.g., doxorubicin,epirubicin, daunorubicin, and idarubicin), adriamycin, dactinomycin,idarubincin, plicamycin, mitomycin, and bleomycin. As with the drugsmentioned above, use of these agents to treat particular types ofcancers is well known in the art, and they can be used in combinationwith halichondrin B analog treatment to treat these and other types ofcancers. As a specific, non-limiting example, an anthracycline, such asdoxorubicin, can be administered in conjunction with halichondrin Btherapy for the treatment of breast or pancreatic cancers.Alternatively, a third agent, cyclophosphamide, can be used in thismethod.

Alkylating agents comprise another class of chemotherapeutic drugs thatcan be administered in conjunction with a halichondrin B analog,according to the invention. Examples of such drugs include procarbazine,dacarbazine, altretamine, cisplatin, carboplatin, and nitrosoureas.Halichondrin B analogs can be used with these agents in the treatment ofcancers that these agents are known in the art to be used to treat, aswell as in the treatment of other cancers. For example, a halichondrin Banalog can be used in conjunction with carboplatinum in the treatment ofnon-small cell lung carcinoma or ovarian cancer.

An additional type of chemotherapeutic drug with which halichondrin Banalogs can be administered, according to the invention, is plantalkaloids, such as vinblastine, vincristine, etoposide, teniposide,topotecan, irinotecan, paclitaxel, and docetaxel. As specific,non-limiting examples, a halichondrin B analog can be used inconjunction with irinotecan for the treatment of colorectal cancer, orwith topotecan in the treatment of ovarian or non-small cell lungcancers.

Further types of anti-cancer agents that can be used in conjunction withhalichondrin B analog treatment, according to the invention, areanticoagulants and antithrombotic agents. For example, heparin (e.g.,low molecular weight heparin or heparin sulfate) or warfarin can beused. Use of these agents in treating patients by, for example,injection or oral administration, is well known in the art, and thusthey can readily be adapted by those of skill in the art for use in thepresent invention.

Numerous approaches for administering anti-cancer drugs are known in theart, and can readily be adapted for use in the present invention. In thecase of one or more drugs that are to be administered in conjunctionwith a halichondrin B analog, for example, the drugs can be administeredtogether, in a single composition, or separately, as part of acomprehensive treatment regimen. For systemic administration, the drugscan be administered by, for example, intravenous infusion (continuous orbolus). Appropriate scheduling and dosing of such administration canreadily be determined by those of skill in this art based on, forexample, preclinical studies in animals and clinical studies (e.g.,phase I studies) in humans. In addition, analysis of treatment usingsimilar drugs, as well as monitoring factors such as blood counts (e.g.,neutrophil and platelet counts) and vital signs in patients can be used,as is well understood in the art.

Many regimens used to administer chemotherapeutic drugs involve, forexample, intravenous administration of a drug (or drugs) followed byrepetition of this treatment after a period (e.g., 1-4 weeks) duringwhich the patient recovers from any adverse side effects of thetreatment. It may be desirable to use both drugs at each administrationor, alternatively, to have some (or all) of the treatments include onlyone drug (or a subset of drugs).

As a specific, non-limiting example of a treatment regimen included inthe invention, a halichondrin B analog (e.g., 0.01-5 mg/m²) can beadministered to a patient by intravenous infusion for 0.5-3 hours,followed by intravenous infusion of another drug (e.g., gemcitabine,e.g., 500-900 mg/m²) for 0.5-3 hours. This course of treatment can berepeated every 2-3 weeks, as determined to be tolerable and effective bythose of skill in the art. In a variation of this method, the treatmentis carried out with both drugs on the first day, as is noted above, butthen is followed up with treatment using only the secondary drug (e.g.,gemcitabine) in ensuing weeks.

Further, as is well known in the art, treatment using the methods of theinvention can be carried out in conjunction with the administration ofantiemetics, which are drugs that are used to reduce the nausea andvomiting that are common side effects of cancer chemotherapy. Examplesof such drugs include major tranquilizers (e.g., phenothiazines, such aschlorpromazine and prochlorperazine), dopamine antagonists (e.g.,metoclopramide), serotonin antagonists (e.g., ondansetron andgranisetron), cannabinoids (e.g., dronabinol), and benzodiazepinesedatives.

In addition to the cancers mentioned above, the methods and compositionsof the invention can be used to treat the following types of cancers, aswell as others: skin (e.g., squamous cell carcinoma, basal cellcarcinoma, or melanoma), prostate, brain and nervous system, head andneck, testicular, lung, liver (e.g., hepatoma), kidney, bladder,gastrointestinal, bone, endocrine system (e.g., thyroid and pituitarytumors), and lymphatic system (e.g., Hodgkin's and non-Hodgkin'slymphomas) cancers. Other types of cancers that can be treated using themethods of the invention include fibrosarcoma, neurectodermal tumor,mesothelioma, epidermoid carcinoma, and Kaposi's sarcoma.

The invention also includes compositions that include a halichondrin Banalog in combination with an additional therapeutic agent(s), such asany of those agents listed above. The drugs in these compositionspreferably are formulated for administration to patients (e.g., inphysiological saline) or, alternatively, can be in a form requiringfurther processing prior to administration. For example, thecompositions can include the drugs in a lyophilized form or in aconcentrated form requiring dilution. Formulation of drugs for use inchemotherapeutic methods can be carried out using standard methods inthe art (see, e.g., Remington's Pharmaceutical Sciences (18^(th)edition), ed. A. Gennaro, 1990, Mack Publishing Co., Easton, Pa.).

What is claimed is:
 1. A compound having the formula:


2. A compound having the formula:


3. A compound having the formula:


4. A compound having the formula:


5. A compound having the formula:


6. A method of preparing:

or a pharmaceutically acceptable salt thereof, the method comprising thesteps of synthesizing a compound selected from the group consisting of

and synthesizing B1939 or the pharmaceutically acceptable salt from thecompound.
 7. A method of preparing:

or a pharmaceutically acceptable salt thereof, the method comprising thesteps of reacting

under conditions to produce:

reacting ER804029 under conditions to produce:

reacting ER804030 under conditions to produce:

reacting B2304 under conditions to produce:

reacting B2303, B2303 under conditions to produce:

reacting B2301 under conditions to produce:

and reacting B1793 under conditions to produce B1939 or thepharmaceutically acceptable salt.